Theoretical evidence for oxygenated intermediates in the reductive cyclization of nitrobenzenes

Org Lett. 2004 Mar 4;6(5):743-6. doi: 10.1021/ol0364273.

Abstract

Deoxygenation of nitroaromatics is a classic synthetic method for the construction of nitrogen heterocycles. The generally accepted mechanism involves exhaustive deoxygenation to a singlet nitrene. We present theoretical evidence for an alternative, 6pi-electron 5-atom electrocyclization of nitroso-styrenes, -stilbenes, and -biphenyls to nitronates. A downstream 1,5-H shift and tautomerization leads to N-hydroxy heterocycles. [reaction: see text]